Recently, with the rapid development of information processing technology, various types of information devices, such as mobile phones and computers, exhibit high performance and have multiple functions and small sizes.
Such an information device generally includes an input device for inputting data, a data processing device for processing input data, and an output device for outputting processed data. Of these devices, the input device is gradually gaining in importance.
However, various current types of input devices have many problems with the input of various data such as characters and instructions. For example, input devices, such as keyboards, used in Personal Computers (PCs) or notebook computers are not suitable for the realization of small sizes because there is a limitation on the possible reduction in size, and touch screen schemes used in Personal Data Assistants (PDAs) and keypad schemes used in mobile phones are inconvenient because the speed of input is slow and erroneous input frequently occurs.
Meanwhile, since the above-described variety of types of input devices must be provided with input means for transferring finger input actions, they are problematic in that the construction thereof is complicated, which makes product design difficult, and the manufacturing cost thereof increases due to the production and management of related component parts.
Furthermore, since a space for the input means is required on the input devices themselves, they are not suitable for the realization of small-sized and slim products and have degraded external appearances due to the input means which protrude from the casing.